Immune outcomes of Zika virus infection in nonhuman primates

Abstract

Although the Zika virus (ZIKV) epidemic is subsiding, immune responses that are important for controlling acute infection have not been definitively characterized. Nonhuman primate (NHP) models were rapidly developed to understand the disease and to test vaccines, and these models have since provided an understanding of the immune responses that correlate with protection during natural infection and vaccination. Here, we infected a small group of male rhesus (Macaca mulatta) and cynomolgus (Macaca fascicularis) macaques with a minimally passaged Brazilian ZIKV isolate and used multicolor flow cytometry and transcriptional profiling to describe early immune patterns following infection. We found evidence of strong innate antiviral responses together with induction of neutralizing antibodies and T cell responses. We also assessed the relative importance of CD8 T cells in controlling infection by carrying out CD8 T cell depletion in an additional two animals of each species. CD8 depletion appeared to dysregulate early antiviral responses and possibly increase viral persistence, but the absence of CD8 T cells ultimately did not impair control of the virus. Together, these data describe immunological trends in two NHP species during acute ZIKV infection, providing an account of early responses that may be important in controlling infection. Zika virus (ZIKV) has been a known pathogen for over half a century 1, but severe disease manifestations were not directly associated with the virus for most of its history. The recent outbreaks of ZIKV in the Western hemisphere became linked to neurologic and congenital syndromes that have provided strong incentives to develop prophylactic and therapeutic countermeasures. Several vaccine candidates spanning multiple platforms have performed well in preclinical studies and have advanced to clinical trials, but the waning of the epidemic has precluded efficacy testing in large populations 2,3. Additionally, an understanding of the immune responses that provide protection during natural infection is not yet complete, which also complicates our ability to evaluate whether vaccines will replicate these protective responses. The immunology of ZIKV infection has been most extensively studied in mice, and murine studies have shown the critical importance of type-I interferon (IFN) in limiting disease together with the protective roles of humoral and T cell responses 4-7. A growing body of literature also describes immune responses following ZIKV infection in nonhuman primates (NHPs), which are often used in preclinical vaccine studies 8 given their genetic and immunologic similarities to humans. Multiple species of macaques have been utilized, and these models replicate clinical aspects of viral infection and disease 9-13. However, the relative importance of innate and adaptive responses in controlling infection in monkeys is only beginning to be explored in depth, and this data is an important open question for the evaluation of candidate vaccines. Here, we carried out a descriptive anal...

Molecular Approaches for the Validation of the Baboon as a Nonhuman Primate Model for the Study of Zika Virus Infection

“…Several genes found to be upregulated in both the Lim 2020 and Schouest 2020 studies were also upregulated (FDR ≤ 0.05 and LFC ≥ 1.0) in our results, including IFI44, IFIT1, IFIT3, MX1, OAS1, and OASL ( Supplemental Figures 4–6 ). Finally, this study demonstrated that subclinical ZIKV infection can induce a protective immune response against re-exposure with an evolutionary distant ZIKV isolate, and that re-exposure to ZIKV induces an anamnestic immune response to the virus, even in the absence of detectable viremia, a finding that has also been reported in rhesus macaque models of ZIKV infection ( Osuna et al., 2016 ; Schouest et al., 2020 ; Schouest et al., 2021 ).…”

“…Transcriptomic profiling of the baboon response to ZIKV infection revealed upregulation of genes associated with IFN alpha, beta, and gamma signaling and antiviral responses between days 0 and 3, then downregulation of the same sets of genes between days 3 and 15, a period when viral infection was effectively controlled. The upregulation of genes related to IFN signaling early in infection has been observed in other studies of ZIKV infection in whole blood of rhesus and cynomolgus macaques ( Schouest et al., 2020 ), as well as in human PBMCs in vitro ( Lim et al., 2020 ). Several genes found to be upregulated in both the Lim 2020 and Schouest 2020 studies were also upregulated (FDR ≤ 0.05 and LFC ≥ 1.0) in our results, including IFI44, IFIT1, IFIT3, MX1, OAS1, and OASL ( Supplemental Figures 4–6 ).…”

Zika virus persistence in the male macaque reproductive tract

“…The tissues evaluated in this study were from healthy male rhesus ( Macaca mulatta ) and cynomolgus ( Macaca fascicularis ) macaques, born at their respective National Primate Research Centers ( Table 1 ). Archived reproductive tissues, including testes, epididymis, seminal vesicle, and prostate gland, from 51 ZIKV-infected and 8 age-matched, uninfected, male rhesus and cynomolgus macaques from past or ongoing collaborative research projects were kindly donated by the California (N = 35) [ 14 , 31 , 32 ], Tulane (N = 10) [ 69 ], Wisconsin (N = 6) [ 70 , 71 ], and Washington (N = 1 uninfected control rhesus macaque) NPRCs. These animals, aged 2 to 15 years old, were inoculated IV or SC with variable ZIKV strains and doses, humanely euthanized, and necropsied at 1 to 60 DPI.…”

Zika virus persistence in the male macaque reproductive tract

“…All studies were approved by the appropriate Institutional Animal Care and Use Committees (IACUC). Archived reproductive tissues, including testes, epididymis, seminal vesicle, and prostate gland, from 51 ZIKV-infected and 8 age-matched, uninfected, male rhesus and cynomolgus macaques from past or ongoing collaborative research projects were kindly donated by the California (N = 35) (13,31,32), Tulane (N = 10) (70), Wisconsin (N = 6) (71, 72), and Washington (N = 1 uninfected control rhesus macaque) NPRCs. These animals, aged 2 to 15 years old, were inoculated IV or SC with variable ZIKV strains and doses, humanely euthanized, and necropsied at 1 to 60 DPI.…”